Polished steel... A Polished or "smooth" steel is used to maintain the edge on a very sharp knife. This Granton brand smooth steel is the most popular commercial packing house steel used in the U S. Used properly and frequently (2 or 3 gentle strokes per side every 5-10 minutes of cutting), this smooth steel will significantly extend the life of your knife between sharpening. Used with a high quality boning knife such as victorinox, you can expect to cut about 10 whole deer between sharpening. FYI-A rough steel is used more as a sharpening tool, whereas a smooth steel maintains a sharp knife for a very long time. That is why a "smooth" steel is preferred in commercial packing houses where they can cut all day without needing to sharpen there knife on a rough steel or a stone. Instructions for using a steel properly is included with the purchase of every steel.